Is Wealthsimple Trade regulated? Are my accounts protected?

Absolutely! Wealthsimple Trade is a division of Canadian ShareOwner Investments Inc., and is a member of the Investment Industry Regulatory Organization of Canada (IIROC) and the Canadian Investor's Protection Fund (CIPF) which protects accounts up to $1,000,000 against insolvency (note that this does not protect against market fluctuations).